1. Field of the Invention
The present invention relates to an imaging apparatus, and, more particularly, to an ink jet printer having a biased platen.
2. Description of the Related Art
Some imaging apparatus, such as a typical ink jet printer, have a reciprocating printhead whereby a printhead carriage carrying the printhead is supported by a pair of carrier guide rods which are positioned substantially traverse to a print media path. As a sheet of print media is transported in an indexed manner under the printhead, the printhead is scanned in a reciprocating manner across the width of an image area on the sheet of print media, wherein the path of the reciprocating printhead defines a print zone. A platen is provided opposite to the printhead for contacting the nonprinted side of the print media and, in part, defines the distance between the printhead and the sheet of print media.
It has been realized that the distance between the plane of the nozzle plate of the printhead and the plane of the print media on which the ink expelled from the nozzle plate is deposited, also known as the printhead to print media gap, can have an impact on the print quality of the ink jet printer. As the gap deviates from the ideal gap, and particularly as a result of a widened gap, an error in dot placement increases. The limits on the low end of the gap range is defined by the point at which the printhead actually contacts the media, thereby causing smearing of the freshly deposited ink. In addition, such contact with the print media can result in damage to the printhead such as, for example, by clogging the nozzles of the nozzle plate of the printhead. Thus, it is desirable in a high quality ink jet printer design to control the printhead to print media gap to a minimum value without permitting contact between the printhead and the print media. However, any variation in the parallelism between the path of the printhead nozzle plate and the plane of the platen results in variations in the printhead to print media gap along the extent of the print zone.
What is needed in the art is a platen system for an imaging apparatus that provides for a substantially uniform printhead to platen gap throughout the print zone, which in turn provides for a substantially uniform printhead to print media gap throughout the print zone.
The present invention provides a platen system for an imaging apparatus that provides for a substantially uniform printhead to platen gap throughout the print zone, which in turn provides for a substantially uniform printhead to print media gap throughout the print zone.
The invention comprises, in one form thereof, an imaging apparatus providing a machine frame including a first side frame and a second side frame, wherein the first side frame is spaced apart from the second side frame. A first plurality of platen mounting members is provided which are spaced apart and extend from the first side frame. A second plurality of platen mounting members is provided which are spaced apart and extend from the second side frame. A platen is positioned to extend between the first side frame and the second side frame. The platen has a first end including a first plurality of engagement members and has a second end including a second plurality of engagement members. A biasing assembly is coupled to the machine frame, wherein the biasing assembly applies a biasing force to the platen to move the first plurality of engagement members into respective engagement with the first plurality of platen mounting members and to move the second plurality of engagement members into respective engagement with the second plurality of platen mounting members.
An advantage of the present invention is that the platen is biased in relation to features precisely located on the side frames of the imaging apparatus, thereby providing for the accurate placement of the platen in relation to a printhead.
Another advantage is that the platen is deflectable to ease the clearing of any media sheet jams.